As a nephew of James Graham, 1st Marquess of Montrose, Napier supported him in his Royalist endeavours.
When in 1650 he sought to return to his home in Scotland, he asked permission of King Charles to rejoin his uncle, and this was granted.
Due to his unflagging Royalist support, he was excepted from Cromwell's Act of Grace on 12 April 1654 and his lands were confiscated by the Commonwealth.
He died in the Netherlands at Delfsham (Delfshaven) in the County of Holland at the beginning of 1660, so did not live to see the Restoration.
[citation needed] Elizabeth Erskine was a prisoner in Edinburgh Castle in August 1645 with her sister-in-law Lilias Napier.